1. Field of the Invention
This invention relates to game balls and more particulary to baseballs and softballs having a thermoplastic core.
2. Description of the Prior Art
Softballs such as are used in both slo-pitch and fast-pitch softball leagues are manufactured in various dimensions with a vast range of physical properties. One common design uses a cork or kapok core wound with synthetic yarn or thread with a cover formed upon the surface of the softball. Typically, the covers are comprised of two pieces which are stitched together. The material of construction for the covers can be either leather, plastic, vinyl or the like. In addition, practice softballs have been manufactured having a core such as previously described with a molded rubber cover to enhance durability. Consequently, the density of the softball along with its attendant properties is determined by its materials of construction and by how tightly the ball is wound. Therefore, there are variables in softball manufacturing which are not capable of adequate control and softball manufacturers have endeavored to find materials of construction sufficient to provide consistency to their product.
Baseballs, as are used in the United States by professional leagues and little leagues, are formed of a cork or rubber core wound with wool yarn and cotton thread, and covered with a stitched, two-piece leather cover. In some instances the cover may be vinyl or rubber, especially in the little leagues where the durability of practice balls is essential. Consequently, the density of the baseball along with its attendant properties is determined by its materials of construction and by how tightly the wool yarn is wound. Therefore, there are variables in baseball manufacturing which are not capable of adequate control and baseball manufacturers have endeavored to find materials of construction sufficient to provide consistency to their product.
In addition, a major factor in the production of softballs and baseballs is the cost of winding cores which involves substantial labor or investment in winding machines.
Confronted with the problem of a uniform product along with increasing labor and capital costs, softball and baseball manufacturers have endeavored to form ball cores of plastic material to solve these problems. Exemplary of such efforts are the teachings of U.S. Pat. No. 3,976,295 and Canadian Pat. No. 632,220. However, as in any sport, participants therein and distributors of such equipment are reluctant to change from existing equipment, and therefore, balls intended to replace the conventional softball and baseball have not received widespread acceptance.
However, in U.S. Pat. No. 4,211,407, a method of forming softballs and baseballs of a single spherical core along with the balls themselves is disclosed wherein such softballs and baseballs have essentially the same characteristics as conventional softballs and baseballs.
Although the softballs produced in accordance with U.S. Pat. No. 4,211,407 are more durable than the conventional softballs, upon prolonged hitting, these softballs, in some instances, develop flat spots. This is a particular problem with respect to softballs which are used in fast-pitch leagues where the striking force on the ball is compounded by the speed at which the ball is pitched.
There are two general types of softballs, one used in fast-pitch and one used in slo-pitch. The slo-pitch balls are referred to as restricted flight balls since they are designed to have less rebound than fast-pitch balls.
In addition, the baseballs produced in accordance with U.S. Pat. No. 4,211,407 have received acceptance, however, they are improved in accordance with the present invention.
In accordance with the present invention, softballs are provided which have excellent playing characteristics which are essentially the same as conventional softballs and additionally have substantially improved durability and do not develop flat spots on prolonged hitting.
Further, baseballs in accordance with the present invention exhibit excellent durability and playing characteristics.